Carbureter.



M. O. CRAWFORD.

OARBURETER.

APPLICATION FILE-D APR. 13, 1914.

Patented Nov. 3, 1914.

ATTORNE Y.

ll-llll 70 Mara-HEW o. omwronn, or nnrnorr, MICHIGAN.

CABIBURETER.

Specification of Letters Patent.

Patented Nov. 3, 191.4.

, Application filed April s, 191;. Serial -1wo.'aa1,43s.

To all whom it may concern:

Be it known that I, Ma'rrrmw O. CRAW- 1 FORD, a citizen of the UnitedStates, residing, at Detroit, county of Wayne, State of Michn. gan, haveinvented'a certain new and useful- Improvement in Carbureters, anddeclare the following to be a full, clear, and exact description of thesame, suchas will enable others skilled in the art towhich it pertainsto make .anduse the same, reference being had to the accompanyingdrawings, which form a partof this specification.

This invention relates to carburetors, and

an object thereof is a carbureterof an improved type and simple formforuse. with Internal combustion engines.

The primary object of my invention is a carburetor in which theconstituent proportions of the gaseous mixture are constant'at allspeeds of the -11101301311131?1S, directly pro-' portional to the themotor. p

A further object. resides in'the means whereby the liquid fuel -isdivided and quantity .of ant drawn into broken up prior to its entranceinto the mix- 1 ing chamber.

A furtherobjectresides in the means employed whereby a rich mixtureispio vided when first starting the engine. y

In the ordinary carbureterthe fuel feed is not directly proportional tothe quantity of air'drawn into the engine, but is excessive at highspeed and insufficient at'low speed by reason of the variationsin' thedegrees of vacuum produced at the various speeds. To obviate this, thefuel. passage is sometimes restricted in area as the throttle is opened,

a and increased with the closing of the throttle, or additional air ismixed with the charge' through operation of spring controlled valves orthe like.

In the invention herein disclosed the desired 'm-ixture regulation isautomatically attained through obtaining the fuel supply,

from two sources, one of which remains constant at all speeds of themotor, and the other of which varies therewith, but which is manuallyregulatable so that the flow may be increased, or diminished as maybefound necessary to produce the best result operation. Both of thesesources of sup 1y are subject to atmospheric pressure and t ecombinedfeed from the two sources produces a uniform mixture at all motor speedsas is hereinafter shown. v

It is also an object of this invention to 1ncorporateihe above objectsin a structure of slmple form and small number of parts.

' These and further objects and novelties of the invention arehereinafter more fully described and claimed and shown in theaccompanying drawings in which F igure 1 1s a plan view of a carbureterem bod mg my invention. Fig. 2 is an end view thereof taken from theintake end. Fig. 8 is a vertical section on line w-w of Fig. 1. Fig. 4is a section taken on line a, b, c, d, of Fig. 1. Fig. 5 is a section online a, e, f, at, of Fig. 1. Fig. 6 is a vertical section on line ez ofFig. 1. Fig. 7 is a diagram showing in a general way the ratio ofgasolene to air from the two sources of supply.

' Similar characters refer to similar parts throughout the drawings andspecification. The device consists of a main conduit 1, and a secondaryconduit 2, both having the form of aVenturi tube, the secondarycondu'it-Q- entering the main conduit-tutor near the. point of greatestrestriction and is thus subject to the variations ixjiressurein the mainconduit. 5

As may be more clearly seen in Figs. 3, 4: and 5, the secondary Nenturi.tube 2 has a cylindrical outer surface and is provided with a flan e 3on the upper end. The tube 2 is inserte in an aperture in the upper wallof the main conduit, tightly fitting therein, the flange limiting theextent of its insertion into the main tube. The secondary tube has arestricted portion 4,.a'1i'dat or near the point of greatestrestriction, upon the outer surface of the tube, is formed a groove orchannel 5. Apertures 6 are formed in the bottom of said groove leadinginto the interior of the tube at such restricted point.

Preferably formed integrally with the main conduit 1 is a float chamber7 in which is a float 8 of any approved form. The float is o erativelyconnected to the pivoted lever 9 w ich has a forked arm 10 engaging in agroove in the head of the stem 11 of the fuel valve 12. The'stem ridesinand is guided by an aperture inthe lug 13 formed atone side of the floatchamber. The fuel enters the float chamber 7 through the conduit 14controlled by the fuel valve and the operabottom. The well 16 is open tothe'full extent being substantially uniform in diameter throughout itslength, while the fuel well 15 at the bottom thereef is restricted beingprovided with a plugQ-17 having a calibrated passageway 18 restrictingthe flow of fuel thereinto from the-fuel chamber asis .hereinaftershown. A certain diameter of the passageway 18 will produce the bestresult with agiven engine and, by forming thepassageway in an insertibleplug, tests may be made with passageways of various diameters and theone that gives the-most effective result determined. Thereaftercarbureters made for such particular sizeand type of em gine maydispense with: the insertible plug, thewell being formed. With-a bottnmandthe passageway formed in the solid wall practically at the samepoint, as in the plug shown in Fig. 4. Leading from near the bot tom ofeach of these wells 15 and 1-6is a passageway 19 and 20 respectively,each' of which terminates in the aperturefor the secondary conduit 2 atthe point registering.

with the groove 5 in said secondary conduit. The normal level of fluidin thesewelle and the fuel chamber is shown bv dotted linesyy in Figs. 1and 5. The well 16 is thread ed at the upper end thereof to receive thethreadedportion 21 of the regulating screw 22 by means of which thecross-sectional area of the passageway 20 may be varied. This screwpasses through an aperture in the cover plate 23 for the fuel chamberregistering with the well 16. The upper end of the well 15' is closed bythe cover plate,'but the well is open to the float chamber above thefluidlevelthrough the aperture 24 in the wall thereof. As shown in Fig.6, the cover plate is apertured at 26- so that the fuel in the fuelchamber 7 is also subject to atmospheric pressure. The head of the fuelvalve may be-provided with a slot to receive a screw-driver blade orlike instrumentto r0 tate the valve and dislodge foreign material or'rind it on its seat.

The flow of air through the conduit 1 is controlled by the butterflyvalve 27 operated in any convenient'manner asby a lever 28 having anadjusting screw 29 limiting the extent to which it may be closed. Asmall conduit or passageway 30is also formed in the upper wall of themain conduit,-'as shown in Figs. 1 and 3, leading into the conduit at apoint 31 just forward of the upper edge of the butterfly valve when inits closed position in which there is a small passageway for air betweenthe-uppenedge of the valve and the Wall of the conduit. Air, in rushingpast the, point 31,- draws the fuel from the conduit 30 which leads intothe aperture for the secondary Venturi tube 2 in registration with thechannel 5 in said tube.

As maybe seen in Fig 4,. the well 15',

fuel supply, is-nearly full of fuel when the engine is at rest, Whilethe amount of fuel which may enter-thewell or chamber 16 and theconnected conduit 20 is considerably less in volume.

In starting the engine with the throttle slightly open as shown in Fig.3, air is drawn past the'outlet 31 of the passageway30, at a high rateof speed, and as the channel 30 is connected with the channel 5surrounding the small secondary tube 2, to which both thewells 15 and 16are connected, fuel from boththese wells 'will be drawninto the maintubewhich results in a very rich mixture desirable at the time of startingthe engine. The fuel in the well 15 will be practically entirely,removed and an amount drawn through the well 16 and the correspondingpassageway, as may be determined'by the aspiratin'g effect of the-airpassing the point 31. As the valve 27 is opened to increasingly greaterextents the aspirating effect at the point 31- gradually ceases and sucheffect at the restricted point of the main conduit 1 increased, beingthe highest atthe time the valve is fully open: or nearly so. Thisproduces a suction in the tube 2,.the greatest as- --pirati-ng effect ofwhich is at the point of greatest restriction, which point isincommunication with the channels 19 and 20, and the corresponding wells15 and 16. As this aspirating effect incrca'sesthe' flow of fluidthrough the conduit 20 increases to-a greater extent. The How to thechannel 5 from the well 15 is constant after the well has first been.emptied, as the flow is produced solely by the weight of liquid in thefuel chamber and restricted by the calibrated passageway 18. This well,being open to atmosphere through the fuel chamber is not altered in rateof How by the aspirating effect at'the discharge end 32 of the tube 2.The well 15 therefore, provides what may be termed a compensating fuelsupply. That is, ,the quantity of fuel delivered into the mainvaporizing tube 1, is the amount delivered from the well 15 and conduit19 combined with that from the well 16 and conduit 20. The quantitydelivered through the conduit; 20 from the well 16 increases inpercentage to the quantity of air, as theispeed of the engine increases,and that flowing from the well 15 thnough the conduit 919 decreases insimilar ratio to the quantity of air drawn into the engine as'it canflow into the well 15 only ate single rate of speed, .and although theflow be. constant its percentage as compared with the volume of air in asingle unit of time increases as the volume of air increases. Therefore,the combined supply from these two sources is exactly in proportion tothe quantity of air drawn in. The result of the use of the two sourcesof supply under the conditions stated may be graphically shown bythediagramFig. 7,

with any particular engine with which the carburetor may be used.

' By use of the small secondary Venturi tube 2 in supplying fuel to themain air conduit, such devices as jets and nozzles may be dispensedwith, and mechanical adjustment of such parts in an attempt to maintainthe proper proportion of the mixture, and other faults incident to theiruse avoided. A jet, as the word indicates, delivers fuel into the airconduit in a stream, and so far as I am aware, the stream always flowsin the same direction as the air pass-- ing through the conduit and auniform mix- .ture of the air and fuel is practically impossible, thefuel in most instances not being completely vaporized until it hasentered the intake manifold of the engine. The fuel feed hereindisclosed is not a jet, as the fuel does not enter the small Venturitube 2 in a stream but the action is similar to that of the smallperfume atomizers commonly in' use in which a stream of air passesdirectly over the mouth of a. supply channel or oi'ifice in a directionat an angle to the direction of the flow of the air which thoroughlybreaks it up into a very fine spray. In the device shown moreparticularly in Fig. 3,

there are several apertures 6 through the wall of the Venturi tube 2leading into thechannel 5, which is in communication with the sources offuel supply. Air in vpassing across the face of these apertures producesa very fine spray which passes out of the Venturi tube 2 at the point32, and is there mixed with air flowing through the conduit 1, producinga uniform gaseous mixture.

The only part to be manipulated is the throttle valve 27, all the otherparts operating automatically without the necessity ofthought upon thepart of the operator, and by arranging the various parts in the generalmanner shown by the drawing, expensive machine work is entirelydispensed with, -as no particularly close fits are required, exceptpossibly in the fitting of the small secondary tube .to prevent leakagealong the surface thereof. The device may be cheaply, made and assembledin proper relation without great care being exercised in the adjustmentof parts relative one to the other, the whole resulting in a veryelficient and inexpensive device.

In what'is known as a 5} carburetertoperating a. 2%214 motor, I havefound the following sizes of conduits to produce a very efficientresult: The main conduit 1 is one inch in diameter, while the restrictedportion thereof is 5 of an inch in diameter. The diameter of therestricted portion of a secondary conduit 2 is of an inch in diam eter,and the fuel conduit 5 thereabout "is of an inch'wide by of an inch deepwith four apertures 6 leading thereinto each of an inch in diameter. Theconduit 30 is j g of an inch in diameter, and the aperture 31leading'thereinto is made by a No. 56 drill. The well 15 is of an inchin diameter and the well 16 is of an inch in diameter, and each of theconduits 19 and 20 are of an inch in diameter. The apermegs leading intothe well 15 in this instance is made by a No. SS-drill. The abovedimensions are given to indicate the relative sizes of the partsmentioned as found eflicient with a certain motor, and it is to beunderstood that these dimensions may be varied to suit variousconditions of operation, sizeof the motor, size of carbureter, etc.

In starting the engine with the throttle very nearly closed and theengine being cranked, the passage of air though the main conduit 1 drawsoil from the wells 15 and 16 into the fuel passage 5. As this air passesby the aperture 31 the high suction occur ring at that point will drawthe oil therethrough into the main conduit, and under this condition ofoperation I have found very little oil enters the main conduit throughthe secondary conduit at 32. Al-

' though high suction occurs at 31, the area of the aperture is so'smallthat such suction is not sufficient of itself to draw oil from the wellsinto the fuel conduit, such result being attained by the passage of theair through the main conduit past the point 32 of the secondary conduit.

lVit-h a half-open throttle the suction at 31 is decreased to a verygreat extent and the suction at 32 is increased by reason of a greaterquantity of air passing thereby than occurs in starting condition.Practically all the fuel with the half-open throttle therefore entersthe main conduit at and although some suction occurs at 31, but lit tleoil passes therethrough. As the oil in the well 15 sinks to the level ofthe bottom of the passage 19 air entering through apertures 26 and 24will mingle with the oil at the base of the passage 19 and the emulsionwill flow up 19 into the fuel conduit 5.

This condition exists whenever the suction through the passageway 19 isgreat enoughto take the oil faster than it may flow through the aperture18 into the well.

At high speed, with a full open throttle, the vacuum at 32 is increasedas is also the vacuum at 4, and while it is possible that this mayinduce a flow of air through the aperture 31- back through the conduit30, and out at, aperture 6, the amount that may thus flow through theconduit 30 is so small as to be of no detriment to the operation of thecarbureter. At high speed the air passing through the main conduitnecessarily produces some suction at 31 but the suction at as 1 the 4may also be much higher. Howeve there are several apertures 6 subjectinfluence of the vacuum at 4 and as with the passageways 19 and 20 aswell as the passageway 30 are in communication with the said aperturesand each similarly subjected to the influence of the vacuum, eachpassageway is not aflected to the same extent as Would be the case ifonly the passageway 30 was subject to such influence. The passage 30being also subject to a partial vacuum at both ends, the flow, if any,to the fuel conduit 5 and apertures 6 through the passageway 30 is soslight as to be of no moment.

Having thus described my invention, its utility and mode of operation,what I claim and desire to secure by Letters Patent of the United Statesis 1. In a carbureter, an air conduit, a fuel conduit subject to theinfluence of air pass ing through the air conduit, a suction controlledfuel feed and a fuel feed giving a constant supply per unit oftimebothsaid feeds discharging into said fuel conduit.

2. In a carbureter, an air conduit, and a fuel conduit dischargingthereinto, said fuel conduit being provided with two sources of .fuelsupply, one providing a supply vari able per unit of time, and oneconstant per unit of time. 7

3. In a carburetor, an air conduit, :1 secondary-air conduit leadingthereinto, a fuel conduit in communication with said secondary conduit,a suction controlled fuel feed supply and a fuel feed constant per unitof time discharging into said fuel conduit.

l. In a carbureter, a. atomizer, a fuel conduit communicating therewith,a suction j stant level fuel: chamber, a fuel conduit subcontrolled fuelsupply, and a fuel supply constant per unit of time both discharginginto the fuel conduit.

5. In a carbureter, in combination with a fuel atomizer, a suctioncontrolled fuel sup.- ply, and'a fuel supply constant per unit'of time,both discharging into the fuel inlet'of the atomizer.

6. In a, carlmireter, an air conduit, 2.

conduit subject to. the influence of airpass ing. through the airconduitand adapted to deliverfuel into the air conduit at an angle to thedirection of the flow of air therethrough, a suction controlled fuelfeed, and a fuel feed supply constant per of time, both discharging intothe fuel conduit.

7. In a carbureter, an air conduita fuel conduit, ubject to theinfluence of air pass ing throh the air conduit, a suction consome mufeed and a fuel feed supply constant per unit of time, both discharginginto the fuel conduit and both being subject to atmospheric pressure.

8. In a carbureter, an air conduit, a fuel conduit subject to theinfluence of air passing through the air conduit, a suction controlledfuel feed, and a fuel feed adapted to deliver a constant supply per unitof time, both said feeds discharging into the fuel conduit, and aconstant level supply chamber for said feed.

9. In a carburetcr, an air conduit, a secondary air conduit leadingthereinto, a fuel conduit subject'to the influence of airpassing throughthe secondary air conduit, a suction controlled fuel feed and a fuelfeed adapted to give a constant supply per unit of time, both said feedsdischarging into the fuel conduit.

10. In a carbureter, an airconduit having the form of a Venturi tube, asecondary air conduit of like form discharging thereinto substantiallyat the point of greatest variation in air pressure, a fuel conduitcommunicating with said secondary air conduit substantially at the pointof greatest variation in air pressure, a fuel supply variable per unitof time, and a fuel supply constant per unit of'time both communicatingwith said fuel conduit.

11. In a carburetor, a throttle controlled air conduit having the formof a Venturi vinto said secondary conduit at the point of greatestvariation in air pressure,' a suction controlled fuel supply, a fuelsupply constant per; unit of time, both supplies being in commimicetionwith the fuel conduit, and apas'sa-ge from said fuel condiut leadinginto the main air conduit in proximity tov the throttle.

12. In a carburetor, an air conduit, a conject to the influence of airpassing through 'the air cond'uit, and two fuel supply wells incommunication with the fue adapted to discharge into the fuel conduit,

chamber the flow to one of said wells being restricted and the flow fromthe other well being regulatable.

13. In a carbureter, a primary air conduit, a constant level fuel supplychamber formed integrally therewith, a secondary air conduit arranged todischarge into said primary air conduit, a fuel conduit subject to theinfluence of air passing through the secondary air conduit, and two fuelwells formed, in the wall between the fuel supply chamber and theprimary airconduit each in communication with both the, fuel conduitandthe fuel supply chamber; the, flew to one of said wells beingrestricted and tle flow from the other well being regulata le.

14. In a carbureter, an air conduit, a constant level fuel supplychamber formed integrally therewith, a secondary air conduit arranged todischarge into the said primary air conduit, a fuel conduit leading intothe secondary air conduit, and two fuel wells formed in the wall betweenthe fuel supply chamber and the primary air conduit, each incommunication with both the fuel conduit and the fuel supply chamber;the flow to one of said wells being restricted and the flow from theother well being regulatable; the well having the restricted flow beingopen to atmosphere through the fuel cham- 1 her.

15. In a carbureter, in combination, a primary air conduit having theform of a Venturi tube, a throttle in said conduit, a constant levelfuel supply chamber formed integrally therewith, va seconda'ry'airconduit fuel supply wells formed in the wall.

between said fuel supply chamber and the primary air conduit, each incommunication with both the fuel conduit and the fuel supply chamber;the flow to one of said wells being restricted and the flow from theother Well being regulatable, and a passage from the fuel conduitleading into the primary air conduit in proximity to the throttle.

In testimony whereof, I sign this specification in the presence of twowitnesses.

MATTHEWV O. CRAWVFORD.

Witnesses:

RUBY L. Coon, CHARLES E. WISNER.

